1. Field of the Invention
The present invention relates to a honeycomb structure, and more particularly, it relates to a honeycomb structure as a catalyst support of a catalyst body in which a time until a catalyst becomes active is short and a purification efficiency is enhanced.
2. Description of Related Art
Heretofore, an exhaust gas purifying device has been suggested in which a catalyst for purification is loaded onto a catalyst support to purify components to be purified which are included in exhaust gases discharged from stationary engines for a car, a construction machine and an industrial purpose, a combustion apparatus, and the like. Examples of the components to be purified include hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). As the catalyst support for such an exhaust gas purifying device, there is used, for example, a honeycomb structure (the honeycomb catalyst support) including porous partition walls with which a plurality of cells are formed to become through channels of a fluid (e.g., see Patent Document 1). The catalyst for purification is loaded onto the surfaces of the partition walls of the honeycomb catalyst support and inner porous surfaces of micropores (hereinafter referred to also as “the pores”).
For the purification of HC, CO and NOx included in the exhaust gas, the purification by a ternary catalyst is effective, and such a ternary catalyst is broadly used in purifying the exhaust gas. A certain degree of high temperature is required so that the ternary catalyst or the like effectively acts. Consequently, how to rapidly raise the temperature of the catalyst loaded onto the honeycomb catalyst support is considered to be important in purifying the exhaust gas. At an initial stage of an operation, for example, at the start of an engine, the ternary catalyst loaded onto the honeycomb catalyst support does not sufficiently perform the purification of HC and CO in the exhaust gas, and is discharged to the outside sometimes, before the ternary catalyst is warmed up to a temperature at which the ternary catalyst effectively acts.
To solve such a problem, heretofore, a countermeasure has been employed to decrease a thickness of each of the partition walls of the honeycomb catalyst support or increase a porosity of the honeycomb catalyst support, thereby decreasing a heat capacity of the honeycomb catalyst support. Consequently, the honeycomb catalyst support is warmed at an early stage by the exhaust gas discharged from a vehicle engine (i.e., the combustion gas), so that the temperature of the catalyst loaded onto the honeycomb catalyst support can be raised earlier. Therefore, also at the initial stage of the operation of the engine, a high purifying function can be obtained.
[Patent Document 1] JP-A-2009-242133